The process products find use, inter alia, as intermediates in the preparation of fuel additives (U.S. Pat. No. 3,275,554; DE-A-21 25 039 and DE-A-36 11 230), surfactants, medicaments and crop protectants, hardeners for epoxy resins, catalysts for polyurethanes, intermediates for preparing quaternary ammonium compounds, plasticizers, corrosion inhibitors, synthetic resins, ion exchangers, textile assistants, dyes, vulcanization accelerants and/or emulsifiers.
U.S. Pat. No. 4,153,581 (Habermann) relates to the amination of alcohols, aldehydes or ketones by means of specific Co/Cu catalysts which comprise Fe, Zn and/or Zr.
U.S. Pat. No. 4,152,353 (Dow) relates to the amination of alcohols, aldehydes or ketones by means of specific Ni/Cu catalysts which comprise Fe, Zn and/or Zr.
EP-A1-382 049 (BASF AG) discloses catalysts which comprise oxygen-containing zirconium, copper, cobalt and nickel compounds, and processes for the hydrogenating amination of alcohols. The preferred zirconium oxide content of these catalysts is from 70 to 80% by weight (loc. cit.: page 2, last paragraph; page 3, 3rd paragraph; examples). Although these catalysts feature good activity and selectivity, they exhibit lifetimes in need of improvement.
EP-A2-514 692 (BASF AG) discloses catalysts comprising copper oxide, nickel oxide, and/or cobalt oxide, zirconium oxide and/or aluminum oxide for the catalytic amination of alcohols in the gas phase with ammonia or primary amines and hydrogen. This patent application teaches that the atomic ratio of nickel to copper in these catalysts must be from 0.1 to 1.0, preferably from 0.2 to 0.5 (cf. loc. cit.: Example 1), since yield-reducing by-products otherwise occur to an increased degree in the amination of alcohols (loc. cit.: Examples 6 and 12). The support used is preferably aluminum oxide (loc. cit.: Examples 1 to 5 and 7 to 11).
EP-A1-696 572 and EP-A-697 395 (both BASF AG) disclose catalysts comprising nickel oxide, copper oxide, zirconium oxide and molybdenum oxide for the catalytic amination of alcohols with nitrogen compounds and hydrogen. Although these catalysts achieve high conversions, they can form by-products which themselves or whose conversion products are troublesome in the workup.
EP-A2-905 122 (BASF AG) describes a process for preparing amines from alcohols and nitrogen compounds using a catalyst whose catalytically active composition comprises oxygen compounds of zirconium, copper and nickel, and no oxygen compounds of cobalt or molybdenum.
EP-A-1 035 106 (BASF AG) relates to the use of catalysts comprising oxygen compounds of zirconium, copper and nickel for preparing amines by aminating hydrogenation of aldehydes or ketones.
EP-A1-963 975 and EP-A2-1 106 600 (both BASF AG) describe processes for preparing amines from, respectively, alcohols and aldehydes or ketones, and nitrogen compounds using a catalyst whose catalytically active composition comprises 22-40% by weight (or 22-45% by weight) of oxygen compounds of zirconium, 1-30% by weight of oxygen compounds of copper and in each case 15-50% by weight (or 5-50% by weight) of oxygen compounds of nickel and cobalt.
WO-A-03/076386 and EP-A1-1 431 271 (both BASF AG) also teach catalysts of the abovementioned type for aminations.
WO-A1-03/051508 (Huntsman Petrochemical Corp.) relates to processes for aminating alcohols using specific Cu/Ni/Zr/Sn catalysts which, in a further embodiment, comprise Cr in place of Zr (see page 4, lines 10-16).
European patent application No. 06101339.7 of Feb. 6, 2006 (BASF AG) describes a process for preparing aminodiglycol (ADG) and morpholine by reacting diethylene glycol (DEG) with ammonia in the presence of a heterogeneous transition metal catalyst, the catalytically active composition of the catalyst, before the treatment with hydrogen, comprising oxygen compounds of aluminum and/or zirconium, copper, nickel and cobalt, and the shaped catalyst body having specific dimensions.
Four parallel European patent applications with the same filing date (all BASF AG) relate to particular doped zirconium dioxide-, copper- and nickel-containing catalysts and to their use in processes for preparing an amine by reacting a primary or secondary alcohol, aldehyde and/or ketone with hydrogen and ammonia, a primary or secondary amine.
When the very active catalysts of the prior art are used, including in particular the catalysts according to EP-A1-696 572, EP-A1-963 975 and EP-A2-1 106 600 (see above), there may be an increased tendency to decarbonylation of the carbonyl function (which may have formed as an intermediate) at elevated temperature in the reactants (alcohols, aldehyde, ketone). The formation of methane by hydrogenation of carbon monoxide (CO) leads, owing to the large amount of heat of hydrogenation released, to a “runaway risk”, i.e. an uncontrolled temperature rise in the reactor. When CO is scavenged by amines, methyl-containing secondary components are formed.
In the amination of diethylene glycol (DEG), there is, for example, an increased tendency to form undesired methoxyethanol or methoxyethylamine.
In the case of the example of the amination of diethylene glycol (DEG), the “decarbonylation” is viewed in particular as the sum of undesired components (methanol, methoxyethanol, methoxyethylamine, N-methylmorpholine and methoxy-ethylmorpholine) which are formed from DEG via methoxyethanol according to the reaction network:

The reaction mechanism of the amination of primary or secondary alcohols is assumed to be that the alcohol is initially dehydrogenated to the corresponding aldehyde at a metal site. In this reaction, the copper is suspected to be of particular significance as a dehydrogenation component. When aldehydes are used for the amination, this step is not needed.
The aldehyde formed or used can be aminated by reaction with ammonia or primary or secondary amine with elimination of water and subsequent hydrogenation. This condensation of the aldehyde with the abovementioned nitrogen compound is suspected to be catalyzed by acidic sites of the catalyst. In an undesired side reaction, the aldehyde can also be decarbonylated, i.e. in that the aldehyde function is eliminated as CO. The decarbonylation or methanization is suspected to take place at a metallic site. The CO is hydrogenated to methane over the hydrogenation catalyst, so that the methane formation indicates the extent of decarbonylation. The decarbonylation forms the abovementioned undesired by-products, for example methoxyethanol and/or methoxyethylamine in the abovementioned case.
The desired condensation of the aldehyde with ammonia or primary or secondary amine and the undesired decarbonylation of the aldehyde are parallel reactions, of which the desired condensation is suspected to be acid-catalyzed, while the undesired decarbonylation is catalyzed by metallic sites.